PURPOSE: To feed an engine with optimum accelerating fuel commensurate to its conditions, by setting an opening variation in a throttle valve operating an accelerating pump at every setting range of throttle opening and thereby operating the accelerating pump, in case of controlling an accelerating solenoid- operate pump for a carburetor.

CONSTITUTION: A solenoid-operated accelerating pump 7 is installed in a carbu retor 1, driving a pump 27 in time of output (24) of a control unit 11, and there by accelerating fuel is discharged as much as the specified quantity. The control unit 11 inputs the opening of a throttle valve 2 and its opening variation from a detector 4. The throttle valve opening is read in at the specified period, and what a case is among the threes that whether (A) opening is below 20 degrees, (B) opening is within the range of 20W40 degrees and (C) opening is more than 40 degrees or not is judged, whereby a throttle opening variation value requiring the separate accelerating fuel at respective ranges is set up in advance, and when it accords with each case, the specified quantity of accelerating fuel is discharged by operation of the solenoid-operate accelerating pump 7.